Weekly Update

Jennifer Otani, Ross Weiss, David Giffen, Erl Svendsen, Owen Olfert and Meghan Vankosky
Categories
Week 4

Week 4 and scouting continues despite the rain, some frost, and all those other crazy springtime things that affect agriculture! Be sure to catch the Insect of the Week – it’s pea leaf weevil! Click to review scouting information for cutworms, wireworms, pea leaf weevil, ladybird beetles, canola and flax scouting charts, Field Heroes, and the 2021 crop protection guides, plus there’s more updated information coming your way this week!

Stay safe and good scouting to you!

Questions or problems accessing the contents of this Weekly Update?  Please contact us so we can connect you to our information. Past “Weekly Updates” can be accessed on our Weekly Update page.

Weekly Wind Trajectory Report for May 28

Ross Weiss, Serge Trudel, Jennifer Otani and Meghan Vankosky
Categories
Week 4

Access background information for how and why wind trajectories are monitored in this post.

1. REVERSE TRAJECTORIES (RT)
Since May 1, 2021 the majority of reverse trajectories that have crossed the prairies originated from the Pacific Northwest (Idaho, Oregon and Washington). For the past two weeks there have been an increasing number of reverse trajectories that moved north from Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Compared to previous years, the number incoming trajectories (May) has increased. Though these US regions can be a source of diamondback moths, the ECCC models predict air movement, not actual occurrence of diamondback moths. It should also be noted that host plants of diamondback moth include all plants in the Brassicacea family, including cruciferous weeds and volunteer canola. These plants are suitable hosts until canola emerges.

Figure 1. The average number (based on a 5 day running average) of reverse trajectories that have crossed the prairies for
the period of May 1 – 27 2021.

a. Pacific Northwest (Idaho, Oregon, Washington) – This week there have been 36 trajectories (44 last week) that have crossed Alberta, Manitoba and Saskatchewan. In previous years, the majority of Pacific Northwest reverse trajectories usually have been reported to pass over southern Alberta. This growing season, PNW trajectories have crossed all parts of the prairies (Fig. 2). Compared to this time last year there has been a significant increase in the number of trajectories that have crossed Manitoba and eastern Saskatchewan.

Figure 2. Total number of dates with reverse trajectories originating over Pacific Northwest (Idaho, Oregon, and Washington) and
have crossed the prairies between March 24 and May 27, 2021.

b. Mexico and southwest USA (Texas, California) – Compared to previous years, there has been a noticeable increase in number of trajectories from the southern US. This week there have been 54 trajectories (15 last week) that originated in Mexico and the southwestern US that have crossed the prairies (Fig. 3).

Figure 3. The total number of dates with reverse trajectories originating over Mexico, California and Texas and have
crossed the prairies between March 24 and May 27, 2021.

c. Oklahoma and Texas – This week there have been 51 trajectories (16 last week) that have passed over Manitoba, Saskatchewan and eastern Alberta that originated in Oklahoma or Texas (Fig. 4).

Figure 4. The total number of dates with reverse trajectories originating over Oklahoma and Texas and have crossed
the prairies between March 24 and May 27, 2021.

d. Kansas and Nebraska – This week there have been 63 trajectories (35 last week) that originated in Kansas or Nebraska that have passed over the prairies (Fig. 5). Relative to the reverse trajectories associated with Oklahoma and Texas, the trajectories from Kansas and Nebraska have crossed further into Alberta.

Figure 5. The total number of dates with reverse trajectories originating over Kansas and Nebraska and have crossed
the prairies between March 24 and May 27, 2021.

2. FORWARD TRAJECTORIES (FT)
a. Forward trajectories, originating from Mexico and USA, have crossed a number of prairie locations since May 1, 2021. This week there has been a decrease in the number of trajectories that are predicted to cross the prairies (Fig. 6). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line). The data suggests that, compared to this week, there may be increased potential for the introduction of DBM to the prairies.

Figure 6. The average number (based on a 5-day running average) of forward trajectories that have crossed
the prairies for the period of May 1- 27, 2021.

Weather synopsis

Ross Weiss, Tamara Rounce, David Giffen, Jennifer Otani and Meghan Vankosky
Categories
Week 4

TEMPERATURE: This past week (May 17-23, 2021) began with hot dry conditions followed by cool/wet conditions (mid-week reports of snow and minimum temperatures less than 0 °C). Most of the prairies had significant rainfall over the weekend. The average temperature across the prairies was 1 °C cooler than normal (Fig. 1). For the second week temperatures were warmest across Manitoba. Temperatures were coolest across western Saskatchewan and most of Alberta.

Figure 1. 7-day average temperature (°C) observed across the Canadian prairies for the period of May 17-23, 2021.

The prairie-wide average 30-day temperature (April 24- May 23) was 0.4 °C less than climate normal values. The warmest temperatures were observed across the southern prairies (Table 1; Fig. 2). The 2021 growing season (April 1 – May 16) has been characterized by near-normal temperatures. Temperatures have been similar across the prairies (Table 2; Fig. 3).

Figure 2. 30-day average temperature (°C) observed across the Canadian prairies for the period of April 24-May 23, 2021.
Figure 3. Growing season average temperature (°C) observed across the Canadian prairies for the period of April 1-May 23, 2021.

The growing degree day map (GDD) (Base 5 ºC, April 1-May 24, 2021) is provided below (Fig. 4) while the growing degree day map (GDD) (Base 10 ºC, April 1-May 24, 2021) is shown in Figure 5.

Figure 4. Growing degree day map (Base 5 °C) observed across the Canadian prairies for the growing season (April 1-May 24, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Figure 5. Growing degree day map (Base 10 °C) observed across the Canadian prairies for the growing season (April 1-May 24, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

Many were uttering the f-word this past week… several areas were on the receiving end of frost and many folks are still watching to see how their crops recover. The lowest temperatures recorded ranged from <-14 to >0 °C (Fig. 6) while the highest temperatures (°C) observed across the Canadian prairies the past seven days ranged from <11 to >25 °C (Fig. 7).

Figure 6. Lowest temperatures (°C) observed across the Canadian prairies the past seven days (May 20-26, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (27May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true
Figure 7. Highest temperatures (°C) observed across the Canadian prairies the past seven days (May 12-18, 2021).
Image has not been reproduced in affiliation with, or with the endorsement of the Government of Canada and was retrieved (19May2021). Access the full map at https://www.agr.gc.ca/DW-GS/current-actuelles.jspx?lang=eng&jsEnabled=true

PRECIPITATION: This week average precipitation for the prairies was 17 mm (Fig. 8). Last week the average was less than 2 mm. Conditions continued to be dry in a large region bounded by Swift Current, Saskatoon and Vegreville as well as central and northern areas of the Peace River region. Rainfall amounts for the period of April 24-May 23 (30-day accumulation) were 88 % of long-term average values. Rainfall was greatest for large areas of Alberta, southern Saskatchewan and southern Manitoba (Table 1; Fig. 9). Average growing season (April 1 – May 23) precipitation was 86 % of normal (Table 1; Fig. 10). The map indicates that conditions continue to be very dry across the Peace River region, east-central Alberta, and west-central Saskatchewan.

Figure 8. 7-day cumulative rainfall (mm) observed across the Canadian prairies for the period of May 17-23, 2021.
Figure 9. 30-day cumulative rainfall (mm) observed across the Canadian prairies for the period of April 24-May 23, 2021.
Figure 10. Growing season cumulative rainfall (mm) observed across the Canadian prairies for the period of April 1-May 23, 2021.

The maps above are all produced by Agriculture and Agri-Food Canada. Growers can bookmark the AAFC Current Conditions Maps for the growing season. Historical weather data can be access at the AAFC Drought Watch Historical website, Environment Canada’s Historical Data website, or your provincial weather network.

Access ALL the PPMN’s Wind Trajectory reports (Weekly and Daily).

Access Environment and Climate Change Canada’s weather radar mapping interface. Options to access preceeding precipitation events include clicking off either an 1 or 3 hours time interval, using an 8-colour or 14-colour index. or changing the base map.

Flea beetles

Ross Weiss, Tamara Rounce, David Giffen, Bob Elliott, Julie Soroka, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 4

Two species, Phyllotreta striolata and P. cruciferae, are the most chronic and economically important flea beetle pests of cruciferous crops in western Canada. Bioclimate simulation models for the two flea beetle species were developed to assess how climatic factors influence shifts in their geographic distribution and relative abundance. Economic risk was associated with populations in the orange and red zones (Figs. 1-4). It is crucial to note that the following information is NOT based on flea beetle densites BUT IS INSTEAD reflecting the suitability of environmental factors for P. striolata and P. cruciferae to prosper in highlighted areas of the following maps.

This spring has been approximately 1 °C cooler than normal. Recent rain (May 23-24) has resulted in precipitation amounts that are normal to above normal (30-day total) across Alberta and Saskatchewan. Simulations were run to determine how the two flea beetle species might respond to cooler, wetter conditions (compared to average growing seasons). Based on average temperature and precipitation (based on long term climate normals) risk associated with P. cruciferae is most prevalent across the southern prairies and risk related to P. striolata tends to be greatest across the Parkland and Peace River regions (Figs. 1 and 2).

Figure 1. Predicted risk for P. cruciferae, for model simulations based on long term climate normals. Red and orange regions may
be associated with economic crop losses.
Figure 2. Predicted risk for P. striolata, for model simulations based on long term climate normals. Red and orange regions may
be associated with economic crop losses.

For both species, cooler/wetter conditions generally could result in reduced risk and southward shifts in distribution (Figs. 3 and 4). Cooler and wetter than average growing seasons were predicted to have less negative impact on P. striolata than P. cruciferae. For example, Peace River populations of P. striolata are predicted to present reduced risk with cooler, wetter conditions (compared to average climate). Under similar conditions, P. cruciferae was predicted to have significantly reduced risk in the Peace River region. Wetter than average conditions in Manitoba may result in reduced risk from P. cruciferae and P. striolata. Olfert et al. (2017) reported that both species were more sensitive to temperature than moisture. Potential risk related to warmer temperatures was greater for P. cruciferae than P. striolata. Producers should monitor flea beetle species composition, crop stage and weather to assess potential flea beetle risk to cruciferous crops.

Figure 3. Predicted risk for P. cruciferae, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.
Figure 4. Predicted risk for P. striolata, for model simulations based on conditions that are cooler and wetter than current climate. Red and orange regions may be associated with economic crop losses.

If flea beetle densities are high, seedling damage levels can advance quickly – even within the same day! The cotyledon stage of canola is vulnerable to flea beetle feeding. Review photos of flea beetle feeding damage posted earlier in the Weekly Update (Wk 02 – May 14, 2021) to help assess percent defoliated and to apply the action threshold of 25 % leaf area of cotyledons consumed plus flea beetles were the Insect of the Week (Wk 02 – May 10)!

Access biological and pest management information posted by Alberta Agriculture and Forestry, Saskatchewan Agriculture, or Manitoba Agriculture and Resource Development, or the Canola Council of Canada’s Canola Encyclopedia. Refer to the flea beetle page within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (Philip et al. 2018) as an English-enhanced or French-enhanced version.

Cereal leaf beetle development

Ross Weiss, Tamara Rounce, David Giffen, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 4

The cereal leaf beetle (CLB) model output predicts that egg hatch may be starting across the prairies. The graphs provide a comparison of development at Saskatoon (Fig. 1) and at Lethbridge (Fig. 2). The simulation indicates that second instar larvae may occur during the last week of May near Saskatoon and Lethbridge.

Figure 1. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Saskatoon, SK
as of May 23, 2021 (projected to June 7, 2021).
Figure 2. Predicted status of cereal leaf beetle (Oulema melanopus) populations near Lethbridge, AB
as of May 23, 2021 (projected to June 7, 2021).

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelterbelts, deciduous and conifer forests. They emerge in the spring once temperatures reach 10-15 ºC and the adults are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  

Figure 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski).

Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the midvein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.  

Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 – 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).

Alfalfa weevil predicted development

Ross Weiss, Tamara Rounce, David Giffen, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 4

Model simulations for alfalfa weevil (AAW) predict that oviposition should be well underway across the prairies. The following graphs indicate that development is similar near Swift Current SK (Fig. 1) and Brandon MB (Fig. 2). The model predicts that that hatch may occur during the last week of May and that second instar larvae could be present during the first week of June.

Figure 1. Projected predicted status of alfalfa weevil (Hypera postica) populations near
Swift Current SK as of May 23, 2021 (projected to June 7, 2021).
Figure 2. Projected predicted status of alfalfa weevil (Hypera postica) populations near
Brandon MB as of May 23, 2021 (projected to June 7, 2021).

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long.  

Figure 3. Developmental stages of the alfalfa weevil (Hypera postica). Composite image: J. Soroka (AAFC-Saskatoon).

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the “Field crop and forage pests and their natural enemies in western Canada – Identification and management field guide” (2018; accessible in either English-enhanced or French-enhanced versions).

Bertha armyworm development

Ross Weiss, Tamara Rounce, David Giffen, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 4

Model simulations to May 23, 2021, indicate that overwintered BAW pupal development (Fig. 1, C) varies across the prairies. Development is predicted to be greatest across the southern prairies (Fig. 2). Based on current development, adult emergence is projected to occur in mid-June.

Figure 1. The egg stage (A), larval stage (B), pupal stage (C), and adult stage (D) of bertha armyworm.
Photos: Jonathon Williams (AAFC-Saskatoon).
Figure 2. Predicted bertha armyworm (Mamestra configurata) pupal development across the Canadian prairies as of May 23, 2021.

Biological and monitoring information related to bertha armyworm in field crops is posted by the provinces of ManitobaSaskatchewanAlberta and the Prairie Pest Monitoring Network. Also refer to the bertha armyworm pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” which is a free downloadable document as both an English-enhanced or French-enhanced version.

Predicted grasshopper development

Ross Weiss, Tamara Rounce, David Giffen, Owen Olfert, Jennifer Otani and Meghan Vankosky
Categories
Week 4

The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).  

Model simulations were used to estimate grasshopper egg development as of May 23, 2021. Average development of eggs is 73 % and is well ahead of the long-term average of 62 %. Since last week, developmental rates increased at all locations. Recent warm conditions across southeastern Saskatchewan and southern Manitoba have been responsible for the advanced development of eggs near Regina, Brandon and Winnipeg (Fig. 1). The simulation predicted that development was greatest across most of the southern prairies (Fig. 2).

Figure 1. Predicted percent embryonic development of grasshopper eggs (Melanoplus sanguinipes) across
the Canadian prairies as of May 23, 2021.
Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 23, 2021.

The model was projected to June 7 to determine potential development at Winnipeg and Lethbridge over the next two weeks (Figs. 3 and 4). Results suggest that by June 7 hatch could be at 20 % for Lethbridge and approximately 35 % near Winnipeg. Drought conditions tend to favour development of grasshopper populations while delaying crop development. If dry conditions persist, crop development may be delayed across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as the hatch progresses in late May and early June.

Figure 3. Projected predicted development of M. sanguinipes populations near Winnipeg, Manitoba as of May 23, 2021 (projected to June 7, 2021).
Figure 4. Projected predicted development of M. sanguinipes populations near Lethbridge, Alberta as of May 23, 2021 (projected to June 7, 2021).

Biological and monitoring information related to grasshoppers in field crops is posted by Manitoba Agriculture and Resource DevelopmentSaskatchewan AgricultureAlberta Agriculture and Forestry, the BC Ministry of Agriculture and the Prairie Pest Monitoring Network.  Also refer to the grasshopper pages within the “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” (accessible in either English-enhanced or French-enhanced versions).

Pestiferous slugs and their parasites

Lien Luong and Jennifer Otani
Categories
Week 4

Researchers based at the University of Alberta are conducting a survey of pestiferous slugs and their associated nematode parasites from agricultural fields of Alberta. Last year, a peer-reviewed article was published (Nematology2020) which reported for the first time the presence of a parasitic nematode in Canada. The parasite can kill slugs and could have a role as a potential biocontrol agent against slug populations.

The slug survey continues this summer with researchers hoping to connect with producers who are interested in participating. If interested, please contact researchers at slugs@ualberta.ca now to participate by:
● Either allowing U of A staff to collect slugs from fields (1-2 times/month) or
● Arranging to send live slugs encountered in the field (please email first to obtain detailed collection instructions).

Email slugs@ualberta.ca to obtain more information.

Figure 1. Flag leaf feeding damage on wheat caused by the grey field slug (Deroceras reticulatum).
Photo taken near Crooked Creek AB on August 2, 2018, by J. Otani.

Provincial insect pest report links

Jennifer Otani, John Gavloski, James Tansey, Carter Peru and Shelley Barkley
Categories
Week 4

Provincial entomologists provide insect pest updates throughout the growing season so link to their information: 

MANITOBA’S Crop Pest Updates for 2021 are now available! Access the May 26, 2021, report here. Be sure to bookmark their Crop Pest Update Index to readily access these reports! Also bookmark their insect pest homepage to access fact sheets and more!

Diamondback moth pheromone trap monitoring update for MB Refer to the summary updated twice a week. So far extremely low numbers have been intercepted in only sixteen traps (e.g., when present, only max. of 8 moths per site) in Manitoba. Read the details on page 5 of the May 26, 2021, report.

SASKATCHEWAN’S Crop Production News will soon be available. Access the new Crops Blog Posts and review Saskatchewan’s 2020 insect pest surveying results in order to prepare for 2021. Be sure to bookmark their insect pest homepage to access important information!

Diamondback moth pheromone trap monitoring update for SK – follow this link to find current DBM counts. At this point, extremely low numbers have been intercepted but monitoring continues. Seven moths were reported across the entire province so far (2021May19 Carter, pers. comm.).

•  ALBERTA’S Alberta Insect Pest Monitoring Network webpage links to insect survey maps, live feed maps, and insect trap set-up videos and more. Reminder – NEW for 2021 – AAF’s Shelley Barkley has gathered and streamlined information into a Major Crops Insect webpage. The new webpage does not replace the Alberta Insect Pest Monitoring Network page. However, the new Major Crops Insect webpage serves as a table of contents, connecting users to crop insect pest information on alberta.ca. It offers links to specific insect identification, life cycle, damage, monitoring and management. Users will hopefully find pertinent insect information with fewer clicks! Remember, AAF’s Agri-News occasionally includes insect-related information or Twitter users can connect to #ABBugChat Wednesdays at 10:00 am.

Diamondback moth pheromone trap monitoring update for AB – Refer to the Live Map which reports 12 sites, each with extremely low numbers, for a total of only 15 moths intercepted (as of 27May2021).

Cutworm reporting tool for AB – Refer to the Live Map which reports two sites with cutworms (as of 27May2021).

Crop report links

Jennifer Otani
Categories
Week 4

Click the provincial name below to link to online crop reports produced by:
Manitoba Agriculture and Resource Development (subscribe to receive OR access a PDF copy of the May 25, 2021 report).
Saskatchewan Agriculture (or access a PDF copy of the May 18-24, 2021 report).
Alberta Agriculture and Forestry (or access a PDF copy of the May 18, 2021 report).

The following crop reports are also available:
• The United States Department of Agriculture (USDA) produces a Crop Progress Report (access a PDF copy of the May 24, 2021 edition).
• The USDA’s Weekly Weather and Crop Bulletin (access a PDF copy of the May 25, 2021 edition).

PEAS AND FABA BEANS BEWARE: THE PEA LEAF WEEVIL IS OUT AND ABOUT

Erl Svendsen, Jennifer Otani and Finch Van Baal
Categories
Week 4
Pea leaf weevil (AAFC)

This week’s “Insect of the Week” is the Pea Leaf Weevil. Larval hosts are field peas and faba beans. Adults can spread to other cultivated and wild legumes, such as alfalfa, beans and lentils. Each adult female lays up to 300 eggs in one summer! The eggs hatch in the soil near developing plants and larvae move to feed on nitrogen-fixing nodules. This results in partial or complete inhibition of nitrogen fixation by the plant, causing poor plant growth. Adults feed on leaves and growing points of seedlings, causing notches in leaf margins.

Adult pea leaf weevil damage, showing crescent shaped notches on the leaf margin (AAFC)

The pea leaf weevil is a slender greyish-brown insect measuring approximately 5 mm in length. These insects can be distinguished by three light-coloured stripes extending length-wise down the thorax and sometimes the abdomen.  All species of Sitona, including the pea leaf weevil, have a short snout. Mature larva grow up to 3.5-5.5 mm long, and are legless and c-shaped with a brown head.

Pea leaf weevil larva (AAFC)

Biological and monitoring information related to pea leaf weevil in field crops is posted by the province of Alberta and in the PPMN monitoring protocol. Also access the Pea leaf weevil page from the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien).


SHARE THIS POST